arsenm added a comment.
In D69979#1738099 <https://reviews.llvm.org/D69979#1738099>, @craig.topper
wrote:
> I checked Redhat 7.4 that's on the server I'm using for work. And I had a
> coworker check his Ubuntu 18.04 system with this program. And both systems
> printed 1f80 as the value of MXCSR which shows FTZ and DAZ are both 0. Are
> you seeing something different?
>
> #include <x86intrin.h>
> #include <stdio.h>
>
> int main() {
> int csr = _mm_getcsr();
> printf("%x\n", csr);
> return 0;
> }
>
I see the value as 1f80. However the test program I wrote suggests the default
is to flush (and what the comments in bug 34994 suggest?):
In default FP mode
neg_subnormal + neg_subnormal: -0x0p+0
neg_subnormal + neg_zero: -0x0p+0
sqrtf subnormal: 0x0p+0
sqrtf neg_subnormal: -0x0p+0
sqrtf neg_zero: -0x0p+0
With denormals disabled
neg_subnormal + neg_subnormal: -0x0p+0
neg_subnormal + neg_zero: -0x0p+0
sqrtf subnormal: 0x0p+0
sqrtf neg_subnormal: -0x0p+0
sqrtf neg_zero: -0x0p+0
With denormals enabled
neg_subnormal + neg_subnormal: -0x1p-126
neg_subnormal + neg_zero: -0x1p-127
sqrtf subnormal: 0x1.6a09e6p-64
sqrtf neg_subnormal: -nan
sqrtf neg_zero: -0x0p+0
With daz only
neg_subnormal + neg_subnormal: -0x0p+0
neg_subnormal + neg_zero: -0x0p+0
sqrtf subnormal: 0x0p+0
sqrtf neg_subnormal: -0x0p+0
sqrtf neg_zero: -0x0p+0
With ftz only
neg_subnormal + neg_subnormal: -0x1p-126
neg_subnormal + neg_zero: -0x0p+0
sqrtf subnormal: 0x1.6a09e6p-64
sqrtf neg_subnormal: -nan
sqrtf neg_zero: -0x0p+0
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